docs: def add_allowance(self, caller):
          """Adds a new allowance for the method.
  
          :param: tuple caller: A tuple indicating where the method was called
          :return: The new ``Allowance``.
          :rtype: Allowance
          """
  
          allowance = Allowance(self._target, self._method_name, caller)
          self._allowances.insert(0, allowance)
          return allowance